Electronic devices such as smart phones, personal digital assistants, location based devices, digital cameras, music players, computers, or transportation, have become an integral part of many daily activities. We take for granted the convenience and utility of these electronic devices and all too often do not appreciate just how much technology is involved in manufacturing integrated circuit packages for integrated circuit devices. Thus, many and various types of packaging, intended for protection, interconnection, or mounting, have been developed for integrated circuit devices.
Integrated circuit dies are conventionally enclosed in plastic packages that provide protection from hostile environments and enable electrical interconnection between the integrated circuit die and an underlying substrate such as a printed circuit board (PCB). The elements of such a package include a metal leadframe, an integrated circuit die, bonding material to attach the integrated circuit die to the leadframe, bond wires that electrically connect pads on the integrated circuit die to individual leads of the leadframe, and a hard plastic encapsulant material that covers the other components and forms the exterior of the package.
The leadframe is the central supporting structure of such a package. A portion of the leadframe is internal to the package (i.e., completely surrounded by the plastic encapsulant). Some or all of the leads of the leadframe can extend beyond the extent of the package or at least provide partial exposure beyond the encapsulant material. This allows the package to be used in electrically connecting the package to another component or next system level. In certain integrated circuit packages, a portion of the die pad of the leadframe also remains exposed within the exterior extents of the package for use as a heat sink.
For purposes of high-volume, low-cost production of integrated circuit packages, a current industry practice is to etch or stamp a thin sheet of metal material to form a panel or strip that defines multiple lead frames in an array of units. A single strip may be formed to include multiple arrays, with each such array including multiple leadframes in a pattern. In a typical integrated circuit package manufacturing process, the integrated circuit dies are mounted and wire bonded to individual leadframes, with the encapsulant material then being applied to the strip to encapsulate the integrated circuit dies, bond wires, and portions of each of the leadframes in the above-described manner. The units usually have all their leads electrically joined together by the leadframe connecting bar, such as rails and edges.
Upon the hardening of the encapsulant material, the leadframes within the strip are cut apart or singulated for purposes of producing the individual integrated circuit packages. Such singulation is typically accomplished via a saw singulation process. In this process, a saw blade is advanced along “saw streets” which extend in prescribed patterns between the leadframes as required to facilitate the separation of the leadframes from each other in the required manner. The advancement of the saw blade along the saw streets concurrently cuts the molded plastic mold cap, thus facilitating the formation of a molded plastic package body upon each of the separated leadframes and electrically isolating each unit from each other.
Electrical test is usually carried out on a single singulated unit, one piece at a time. Testing all units within the strip while it is still in strip form (rather than singularly) will definitely increase testing cycle time. This is however not possible without first doing an electrical isolation process, while still maintaining the strip form. Such an isolation process is usually carried out using partial singulation (or half-cutting) which cuts through the connecting bar. Such isolation process however, is quite messy because it makes the leadframe flimsy and breakable, mainly because it has cut through most of what used to stiffen the leadframe structure (that is the leadframe rails and edges).
As is well known in the field of integrated circuit packaging, a leadframe is used as a die carrier in a leadless package for smaller footprint and lower manufacturing cost. However, after singulation, a leadless integrated circuit package still needs to go through final test via individual test socket for the verification of the electrical performance; therefore, the cost of final test cannot be reduced. To date, leadframe panels or strips cannot withstand the stresses encountered in current testing. There continue to be concerns regarding testing of a matrix of a leadless leadframe before singulation. A new approach must be found in order to increase the efficiency of testing integrated circuit packages.
Thus, a need still remains for an integrated circuit package system to improve testing efficiency. In view of the ever-increasing commercial competitive pressures, along with growing consumer expectations and the diminishing opportunities for meaningful product differentiation in the marketplace, it is critical that answers be found for these problems. Additionally, the need to save costs, improve efficiencies and performance, and meet competitive pressures, adds an even greater urgency to the critical necessity for finding answers to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.